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Carlson ML, Stoddard MC. Evolution of Plumage Patterns in a Pattern Morphospace: A Phylogenetic Analysis of Melanerpine Woodpeckers. Am Nat 2024; 203:55-72. [PMID: 38207134 DOI: 10.1086/727508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
AbstractPlumage patterns of melanerpine (Melanerpes-Sphyrapicus) woodpeckers are strikingly diverse. Understanding the evolution and function of this diversity is challenging because of the difficulty of quantifying plumage patterns. We use a three-dimensional space to characterize the evolution of melanerpine achromatic plumage patterns. The axes of the space are three pattern features (spatial frequency, orientation, and contrast) quantified using two-dimensional fast Fourier transformation of museum specimen images. Mapping plumage in pattern space reveals differences in how species and subclades occupy the space. To quantify these differences, we derive two new measures of pattern: pattern diversity (diversity across plumage patches within a species) and pattern uniqueness (divergence of patterns from those of other species). We estimate that the melanerpine ancestor had mottled plumage and find that pattern traits across patches and subclades evolve at different rates. We also find that smaller species are more likely to display horizontal face patterning. We promote pattern spaces as powerful tools for investigating animal pattern evolution.
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Wear K. Scattering in Cancellous Bone. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1364:163-175. [DOI: 10.1007/978-3-030-91979-5_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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3
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Birdi J, Muraleedharan A, D'hooge J, Bertrand A. Fast linear least-squares method for ultrasound attenuation and backscatter estimation. ULTRASONICS 2021; 116:106503. [PMID: 34171752 DOI: 10.1016/j.ultras.2021.106503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 05/13/2021] [Accepted: 06/08/2021] [Indexed: 06/13/2023]
Abstract
The ultrasonic attenuation and backscatter coefficients of tissues are relevant acoustic parameters due to their wide range of clinical applications. In this paper, a linear least-squares method for the estimation of these coefficients in a homogeneous region of interest based on pulse-echo measurements is proposed. The method efficiently fits an ultrasound backscattered signal model to the measurements in both the frequency and depth dimension simultaneously at a low computational cost. It is demonstrated that the inclusion of depth information has a positive effect particularly on the accuracy of the estimated attenuation. The sensitivity of the attenuation and backscatter coefficients' estimates to several predefined parameters such as the window length, window overlap and usable bandwidth of the spectrum is also studied. Comparison of the proposed method with a benchmark approach based on dynamic programming highlights better performance of our method in estimating these coefficients, both in terms of accuracy and computation time. Further analysis of the computation time as a function of the predefined parameters indicates our method's potential to be used in real-time clinical settings.
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Affiliation(s)
- Jasleen Birdi
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium.
| | - Arun Muraleedharan
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium; Department of Electrical Engineering (ESAT), KU Leuven, Leuven, Belgium
| | - Jan D'hooge
- Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium
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Hoffmeister BK, Gray AJ, Sharp PC, Fairbanks LC, Huang J. Ultrasonic Bone Assessment Using the Backscatter Amplitude Decay Constant. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:2412-2423. [PMID: 32553693 DOI: 10.1016/j.ultrasmedbio.2020.04.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 03/29/2020] [Accepted: 04/26/2020] [Indexed: 06/11/2023]
Abstract
Ultrasonic backscatter techniques are being developed to detect changes in bone caused by osteoporosis. The present study introduces a new technique that measures the exponential decay in the amplitude of the backscatter signal quantified by a parameter called the backscatter amplitude decay constant (BADC). Measurements were performed on 54 specimens of cancellous bone from 14 human femurs using a 3.5-MHz transducer. Six methods were tested to determine BADC. The recommended method measures the time slope of the natural log of the rectified signal. Measured values of BADC ranged from approximately 0.1 μs-1 to 0.6 μs-1. Moderate to strong correlations (Spearman's ρ >0.7) were found between BADC and the density and microstructural characteristics of the specimens determined using X-ray microcomputed tomography. The results of this study suggest that BADC may be able to detect changes in the density and microstructure of cancellous bone caused by osteoporosis and other diseases.
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Affiliation(s)
| | - Aubrey J Gray
- Department of Physics, Rhodes College, Memphis, Tennessee, USA
| | - Phoebe C Sharp
- Department of Physics, Rhodes College, Memphis, Tennessee, USA
| | | | - Jinsong Huang
- University of Tennessee Health Science Center, Memphis, Tennessee, USA
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A Combined Ultrasonic Backscatter Parameter for Bone Status Evaluation in Neonates. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2020; 2020:3187268. [PMID: 32411279 PMCID: PMC7211244 DOI: 10.1155/2020/3187268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 03/30/2020] [Indexed: 11/18/2022]
Abstract
Metabolic bone disease (MBD) is one of the major complications of prematurity. Ultrasonic backscatter technique has the potential to be a portable and noninvasive method for early diagnosis of MBD. This study firstly applied CAS to neonates, which was defined as a linear combination of the apparent integrated backscatter coefficient (AIB) and spectral centroid shift (SCS). The objective was to evaluate the feasibility of ultrasonic backscatter technique for assessing neonatal bone health using AIB, SCS, and CAS. Ultrasonic backscatter measurements at 3.5 MHz, 5.0 MHz, and 7.5 MHz were performed on a total of 505 newborns within 48 hours after birth. The values of backscatter parameters were calculated and compared among gestational age groups. Correlations between backscatter parameters, gestational age, anthropometric indices, and biochemical markers were analyzed. The optimal predicting models for CAS were determined. The results showed term infants had lower SCS and higher AIB and CAS than preterm infants. Gestational age and anthropometric indices were negatively correlated with SCS (|r| = 0.45 – 0.57, P < 0.001), and positively correlated with AIB (|r| = 0.36 – 0.60, P < 0.001) and CAS (|r| = 0.56 – 0.69, P < 0.001). Biochemical markers yielded weak or nonsignificant correlations with backscatter parameters. CAS had relatively stronger correlations with the neonatal variables than AIB and SCS. At 3.5 MHz and 5.0 MHz, only gestational age (P < 0.001) independently contributed to the measurements of CAS, and could explain up to 40.5% – 44.3% of CAS variation. At 7.5 MHz, the combination of gestational age (P < 0.001), head circumference (P = 0.002), and serum calcium (P = 0.037) explained up to 40.3% of CAS variation. This study suggested ultrasonic backscatter technique was feasible to evaluate neonatal bone status. CAS was a promising parameter to provide more information about bone health than AIB or SCS alone.
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Wear KA. Mechanisms of Interaction of Ultrasound With Cancellous Bone: A Review. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:454-482. [PMID: 31634127 PMCID: PMC7050438 DOI: 10.1109/tuffc.2019.2947755] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Ultrasound is now a clinically accepted modality in the management of osteoporosis. The most common commercial clinical devices assess fracture risk from measurements of attenuation and sound speed in cancellous bone. This review discusses fundamental mechanisms underlying the interaction between ultrasound and cancellous bone. Because of its two-phase structure (mineralized trabecular network embedded in soft tissue-marrow), its anisotropy, and its inhomogeneity, cancellous bone is more difficult to characterize than most soft tissues. Experimental data for the dependencies of attenuation, sound speed, dispersion, and scattering on ultrasound frequency, bone mineral density, composition, microstructure, and mechanical properties are presented. The relative roles of absorption, scattering, and phase cancellation in determining attenuation measurements in vitro and in vivo are delineated. Common speed of sound metrics, which entail measurements of transit times of pulse leading edges (to avoid multipath interference), are greatly influenced by attenuation, dispersion, and system properties, including center frequency and bandwidth. However, a theoretical model has been shown to be effective for correction for these confounding factors in vitro and in vivo. Theoretical and phantom models are presented to elucidate why cancellous bone exhibits negative dispersion, unlike soft tissue, which exhibits positive dispersion. Signal processing methods are presented for separating "fast" and "slow" waves (predicted by poroelasticity theory and supported in cancellous bone) even when the two waves overlap in time and frequency domains. Models to explain dependencies of scattering on frequency and mean trabecular thickness are presented and compared with measurements. Anisotropy, the effect of the fluid filler medium (marrow in vivo or water in vitro), phantoms, computational modeling of ultrasound propagation, acoustic microscopy, and nonlinear properties in cancellous bone are also discussed.
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Mohanty K, Yousefian O, Karbalaeisadegh Y, Ulrich M, Grimal Q, Muller M. Artificial neural network to estimate micro-architectural properties of cortical bone using ultrasonic attenuation: A 2-D numerical study. Comput Biol Med 2019; 114:103457. [PMID: 31600691 PMCID: PMC6817400 DOI: 10.1016/j.compbiomed.2019.103457] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 01/10/2023]
Abstract
The goal of this study is to estimate micro-architectural parameters of cortical porosity such as pore diameter (φ), pore density (ρ) and porosity (ν) of cortical bone from ultrasound frequency dependent attenuation using an artificial neural network (ANN). First, heterogeneous structures with controlled pore diameters and pore densities (mono-disperse) were generated, to mimic simplified structure of cortical bone. Then, more realistic structures were obtained from high resolution CT scans of human cortical bone. 2-D finite-difference time-domain simulations were conducted to calculate the frequency-dependent attenuation in the 1-8 MHz range. An ANN was then trained with the ultrasonic attenuation at different frequencies as the input feature vectors while the output was set as the micro-architectural parameters (pore diameter, pore density and porosity). The ANN is composed of three fully connected dense layers with 24, 12 and 6 neurons, connected to the output layer. The dataset was trained over 6000 epochs with a batch size of 16. The trained ANN exhibits the ability to predict the micro-architectural parameters with high accuracy and low losses. ANN approaches could potentially be used as a tool to help inform physics-based modelling of ultrasound propagation in complex media such as cortical bone. This will lead to the solution of inverse-problems to retrieve bone micro-architectural parameters from ultrasound measurements for the non-invasive diagnosis and monitoring osteoporosis.
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Affiliation(s)
- Kaustav Mohanty
- Department of Mechanical and Aerospace Engineering, NC State University, Raleigh, NC, 27695, USA.
| | - Omid Yousefian
- Department of Mechanical and Aerospace Engineering, NC State University, Raleigh, NC, 27695, USA.
| | - Yasamin Karbalaeisadegh
- Department of Mechanical and Aerospace Engineering, NC State University, Raleigh, NC, 27695, USA.
| | - Micah Ulrich
- Department of Mechanical and Aerospace Engineering, NC State University, Raleigh, NC, 27695, USA.
| | - Quentin Grimal
- Sorbonne Université, INSERM UMR S 1146, CNRS UMR 7371, Laboratoire d'Imagerie Biomédicale, 75006, Paris, France.
| | - Marie Muller
- Department of Mechanical and Aerospace Engineering, NC State University, Raleigh, NC, 27695, USA.
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Shim J, Hur D, Kim H. Spectral analysis framework for compressed sensing ultrasound signals. J Med Ultrason (2001) 2019; 46:367-375. [PMID: 30955147 DOI: 10.1007/s10396-019-00940-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 02/22/2019] [Indexed: 10/27/2022]
Abstract
PURPOSE Compressed sensing (CS) is the theory of the recovery of signals that are sampled below the Nyquist sampling rate. We propose a spectral analysis framework for CS data that does not require full reconstruction for extracting frequency characteristics of signals by an appropriate basis matrix. METHODS The coefficients of a basis matrix already contain the spectral information for CS data, and the proposed framework directly utilizes them without completely restoring original data. We apply three basis matrices, i.e., DCT, DFT, and DWT, for sampling and reconstructing processes, subsequently estimating the attenuation coefficients to validate the proposed method. The estimation accuracy and precision, as well as the execution time, are compared using the reference phantom method (RPM). RESULTS The experiment results show the effective extraction of spectral information from CS signals by the proposed framework, and the DCT basis matrix provides the most accurate results while minimizing estimation variances. The execution time is also reduced compared with that of the traditional approach, which completely reconstructs the original data. CONCLUSION The proposed method provides accurate spectral analysis without full reconstruction. Since it effectively utilizes the data storage and reduces the processing time, it could be applied to small and portable ultrasound systems using the CS technique.
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Affiliation(s)
- Jaeyoon Shim
- Department of Electrical Engineering, Kwangwoon University, Wolgye-dong Nowon-gu, Seoul, 139-701, Korea
| | - Don Hur
- Department of Electrical Engineering, Kwangwoon University, Wolgye-dong Nowon-gu, Seoul, 139-701, Korea
| | - Hyungsuk Kim
- Department of Electrical Engineering, Kwangwoon University, Wolgye-dong Nowon-gu, Seoul, 139-701, Korea.
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Li Y, Li B, Li Y, Liu C, Xu F, Zhang R, Ta D, Wang W. The Ability of Ultrasonic Backscatter Parametric Imaging to Characterize Bovine Trabecular Bone. ULTRASONIC IMAGING 2019; 41:271-289. [PMID: 31307317 DOI: 10.1177/0161734619862190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The ultrasonic backscatter technique holds the promise of characterizing bone density and microstructure. This paper conducts ultrasonic backscatter parametric imaging based on measurements of apparent integrated backscatter (AIB), spectral centroid shift (SCS), frequency slope of apparent backscatter (FSAB), and frequency intercept of apparent backscatter (FIAB) for representing trabecular bone mass and microstructure. We scanned 33 bovine trabecular bone samples using a 7.5 MHz focused transducer in a 20 mm × 20 mm region of interest (ROI) with a step interval of 0.05 mm. Images based on the ultrasonic backscatter parameters (i.e., AIB, SCS, FSAB, and FIAB) were constructed to compare with photographic images of the specimens as well as two-dimensional (2D) μ-CT images from approximately the same depth and location of the specimen. Similar structures and trabecular alignments can be observed among these images. Statistical analyses demonstrated that the means and standard deviations of the ultrasonic backscatter parameters exhibited significant correlations with bone density (|R| = 0.45-0.78, p < 0.01) and bone microstructure (|R| = 0.44-0.87, p < 0.001). Some bovine trabecular bone microstructure parameters were independently associated with the ultrasonic backscatter parameters (ΔR2 = 4.18%-44.45%, p < 0.05) after adjustment for bone apparent density (BAD). The results show that ultrasonic backscatter parametric imaging can provide a direct view of the trabecular microstructure and can reflect information about the density and microstructure of trabecular bone.
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Affiliation(s)
- Ying Li
- 1 Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Boyi Li
- 1 Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Yifang Li
- 1 Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Chengcheng Liu
- 2 Institute of Acoustics, Tongji University, Shanghai, China
| | - Feng Xu
- 1 Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Rong Zhang
- 3 Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China
| | - Dean Ta
- 1 Department of Electronic Engineering, Fudan University, Shanghai, China
- 4 Key Laboratory of Medical Imaging Computing and Computer Assisted Intervention (MICCAI) of Shanghai, Shanghai, China
- 5 Human Phenome Institute, Fudan University, Shanghai, China
| | - Weiqi Wang
- 1 Department of Electronic Engineering, Fudan University, Shanghai, China
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Deeba F, Ma M, Pesteie M, Terry J, Pugash D, Hutcheon JA, Mayer C, Salcudean S, Rohling R. Attenuation Coefficient Estimation of Normal Placentas. ULTRASOUND IN MEDICINE & BIOLOGY 2019; 45:1081-1093. [PMID: 30685076 DOI: 10.1016/j.ultrasmedbio.2018.10.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 09/18/2018] [Accepted: 10/10/2018] [Indexed: 06/09/2023]
Abstract
Attenuation coefficient estimation has the potential to be a useful tool for placental tissue characterization. A current challenge is the presence of inhomogeneities in biological tissue that result in a large variance in the attenuation coefficient estimate (ACE), restricting its clinical utility. In this work, we propose a new Attenuation Estimation Region Of Interest (AEROI) selection method for computing the ACE based on the (i) envelope signal-to-noise ratio deviation and (ii) coefficient of variation of the transmit pulse bandwidth. The method was first validated on a tissue-mimicking phantom, for which an 18%-21% reduction in the standard deviation of ACE and a 14%-24% reduction in the ACE error, expressed as a percentage of reported ACE, were obtained. A study on 59 post-delivery clinically normal placentas was then performed. The proposed AEROI selection method reduced the intra-subject standard deviation of ACE from 0.72 to 0.39 dB/cm/MHz. The measured ACE of 59 placentas was 0.77 ± 0.37 dB/cm/MHz, which establishes a baseline for future studies on placental tissue characterization.
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Affiliation(s)
- Farah Deeba
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Manyou Ma
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Mehran Pesteie
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jefferson Terry
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Denise Pugash
- Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer A Hutcheon
- Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chantal Mayer
- Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Septimiu Salcudean
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada
| | - Robert Rohling
- Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, British Columbia, Canada; Department of Mechanical Engineering, University of British Columbia, Vancouver, British Columbia, Canada
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Liu C, Li B, Diwu Q, Li Y, Zhang R, Ta D, Wang W. Relationships of Ultrasonic Backscatter With Bone Densities and Microstructure in Bovine Cancellous Bone. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2018; 65:2311-2321. [PMID: 30575524 DOI: 10.1109/tuffc.2018.2872084] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
This study was designed to investigate the associations among ultrasonic backscatter, bone densities, and microstructure in bovine cancellous bone. Ultrasonic backscatter measurements were performed on 33 bovine cancellous bone specimens with a 2.25-MHz transducer. Ultrasonic apparent backscatter parameters ("apparent" means not compensating for ultrasonic attenuation and diffraction) were calculated with optimal signals of interest. The results showed that ultrasonic backscatter was significantly related to bone densities and microstructure ( R2 = 0.17 -0.88 and ). After adjusting the correlations by bone mineral density (BMD), the bone apparent density (BAD) and some trabecular structural features still contributed significantly to the adjusted correlations, with moderate additional variance explained ( ∆R2 = 9.7 % at best). Multiple linear regressions revealed that both BAD and trabecular structure contributed significantly and independently to the prediction of ultrasound backscatter (adjusted R2 = 0.75 -0.89 and ), explaining an additional 14% of the variance at most, compared with that of BMD measurements alone. The results proved that ultrasonic backscatter was primarily determined by BAD, not BMD, but the combination of bone structure and densities could achieve encouragingly better performances (89% of the variance explained at best) in predicting backscatter properties. This study demonstrated that ultrasonic apparent backscatter might provide additional density and structural features unrelated to current BMD measurement. Therefore, we suggest that ultrasonic backscatter measurement could play a more important role in cancellous bone evaluation.
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Liu C, Xu F, Ta D, Tang T, Jiang Y, Dong J, Wang WP, Liu X, Wang Y, Wang WQ. Measurement of the Human Calcaneus In Vivo Using Ultrasonic Backscatter Spectral Centroid Shift. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2016; 35:2197-2208. [PMID: 27562978 DOI: 10.7863/ultra.15.03030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 01/05/2016] [Indexed: 06/06/2023]
Abstract
OBJECTIVES The aim of this study was to determine the relationship between the backscattered spectral centroid shift and the bone mineral density (BMD) in vivo and investigate the feasibility of using the backscattered spectral centroid shift to characterize the cancellous bone status. METHODS Ultrasonic backscatter measurements were performed in vivo on 1216 participants at the right calcaneus using an ultrasonic backscattered bone diagnostic system, and the backscattered spectral centroid shift was calculated at central frequencies of 3.5 and 5.0 MHz. The BMD values were measured at the sites of the lumbar spine and left hip by dual energy x-ray absorptiometry. RESULTS The study population included 592 male and 624 female participants aged 20 to 89 years. The correlations between the backscattered spectral centroid shift in the calcaneus and the spine and hip BMD were found to be statistically significant in both the male and female groups (P < .0001). Linear regression showed that the spectral centroid shift at 3.5 MHz had negative correlations with the spine BMD (R = -0.65 for male participants; R = -0.67 for female participants) and hip BMD (R = -0.64 for male participants; R = -0.64 for female participants). The spectral centroid shift at 5.0 MHz was also found to be closely related to the spine BMD (R = -0.68 for male participants; R = -0.68 for female participants) and hip BMD (R = -0.66 for male participants; R = -0.64 for female participants). CONCLUSIONS The moderate correlations observed between the spectral centroid shift and the spine and hip BMD demonstrate that the ultrasonic backscattered spectral centroid shift may be a useful measurement for assessment of the cancellous bone status.
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Affiliation(s)
- Chengcheng Liu
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Feng Xu
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Dean Ta
- Department of Electronic Engineering, Fudan University, Shanghai, China, Key Laboratory of Medical Imaging Computing and Computer-Assisted Intervention, Shanghai, China
| | - Tao Tang
- Department of Electronic Engineering, Fudan University, Shanghai, China
| | - Yunqi Jiang
- Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jian Dong
- Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Wen-Ping Wang
- Department of Ultrasonography, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Xindang Liu
- Department of Nuclear Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Yi Wang
- Department of Ultrasonography, Huashan Hospital, Fudan University, Shanghai, China
| | - Wei-Qi Wang
- Department of Electronic Engineering, Fudan University, Shanghai, China
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Hoffmeister BK, Smathers MR, Miller CJ, McPherson JA, Thurston CR, Spinolo PL, Lee SR. Backscatter-difference Measurements of Cancellous Bone Using an Ultrasonic Imaging System. ULTRASONIC IMAGING 2016; 38:285-97. [PMID: 26416839 PMCID: PMC4809788 DOI: 10.1177/0161734615603703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Backscatter-difference measurements may be used to detect changes in bone caused by osteoporosis. The backscatter-difference technique measures the power difference between two portions of an ultrasonic backscatter signal. The goal of this study is to evaluate the feasibility of using an ultrasonic imaging system to perform backscatter-difference measurements of bone. Ultrasonic images and backscatter signals were acquired from 24 specimens of human cancellous bone. The signals were analyzed in the frequency domain to determine the normalized mean backscatter-difference (nMBD) and in the time domain to determine the normalized backscatter amplitude ratio (nBAR). The images were analyzed to determine the normalized pixel value difference (nPVD), which measures the difference in average pixel brightness between regions of interest placed at two different depths in the image. All three parameters were found to increase with bone mineral density. The signal-based parameters, nMBD and nBAR, correlated well with bone mineral density, yielding linear correlation coefficients that ranged from 0.74 to 0.87. The image based parameter, nPVD, performed somewhat less well, yielding correlation coefficients that ranged from 0.42 to 0.81. These results suggest that ultrasonic imaging systems may be used to perform backscatter-difference measurements for the purpose of ultrasonic bone assessment.
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Affiliation(s)
| | | | | | | | | | | | - Sang-Rok Lee
- Department of Kinesiology & Dance, New Mexico State University, Las Cruces, NM, USA
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14
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Correlation between the combination of apparent integrated backscatter–spectral centroid shift and bone mineral density. J Med Ultrason (2001) 2016; 43:167-73. [DOI: 10.1007/s10396-015-0690-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 11/11/2015] [Indexed: 10/22/2022]
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15
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Nasief HG, Rosado-Mendez IM, Zagzebski JA, Hall TJ. Acoustic Properties of Breast Fat. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2015; 34:2007-16. [PMID: 26446820 PMCID: PMC4618705 DOI: 10.7863/ultra.14.07039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 02/11/2015] [Indexed: 05/05/2023]
Abstract
OBJECTIVES The American College of Radiology Breast Imaging Reporting and Data System (BI-RADS) atlas for ultrasound (US) qualitatively describes the echogenicity and attenuation of a mass, where fat lobules serve as a standard for comparison. This study aimed to estimate acoustic properties of breast fat under clinical imaging conditions to determine the degree to which properties vary among patients. METHODS Twenty-four women with solid breast masses scheduled for biopsy were scanned with a Siemens S2000 scanner and 18L6 linear array transducer (Siemens Medical Solutions, Malvern, PA). Offline analysis estimated the attenuation coefficient and backscatter coefficients (BSCs) from breast fat using the reference phantom method. The average BSC was calculated over 6 to 12 MHz to objectively quantify the BI-RADS US echo pattern descriptor, and effective scatterer diameters were also estimated. RESULTS A power law fit to the attenuation coefficient versus frequency yielded an attenuation coefficient of 1.28 dB·cm(-1) MHz(-0.73). The mean attenuation coefficient versus frequency slope ± SD at 7 MHz was 0.73 ± 0.23 dB·cm(-1) MHz(-1), in agreement with previously reported values. The BSC versus frequency showed close agreement among all patients, both in magnitude and frequency dependence, with a power law fit of (0.6 ± 0.25) ×10(-4) sr(-1) cm(-1) MHz(-2.49). The average backscatter in the 6-12-MHz range was 0.004 ± 0.002 sr(-1) cm(-1). The mean effective scatterer diameter for fat was 60.2 ± 9.5 μm. CONCLUSIONS The agreement in parameter estimates for breast fat among these patients supports the use of fat as a standard for comparison with tumors. Results also suggest that objective quantification of these BI-RADS US descriptors may reduce subjectivity when interpreting B-mode image data.
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Affiliation(s)
| | | | - James A Zagzebski
- Medical Physics Department, University of Wisconsin, Madison, Wisconsin USA
| | - Timothy J Hall
- Medical Physics Department, University of Wisconsin, Madison, Wisconsin USA
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16
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Heo S, Hur D, Kim H. Optimization of the autocorrelation weighting function for the time-domain calculation of spectral centroids. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2015; 62:421-427. [PMID: 25768811 DOI: 10.1109/tuffc.2014.006416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Spectral centroid from the backscattered ultrasound provides important information about the attenuation properties of soft tissues and Doppler effects of blood flows. Because the spectral centroid is originally determined from the power spectrum of backscattered ultrasound signals in the frequency domain, it is natural to calculate it after converting time-domain signals into spectral domain signals, using the fast Fourier transform (FFT). Recent research, however, derived the time-domain equations for calculating the spectral centroid using a Parseval's theorem, to avoid the calculation of the Fourier transform. The work only presented the final result, which showed that the computational time of the proposed time-domain method was 4.4 times faster than that of the original FFT-based method, whereas the average estimation error was negligible. In this paper, we present the optimal design of the autocorrelation weighting function, which is used for the timedomain spectral centroid estimation process, to reduce the computational time significantly. We also carry out a comprehensive analysis of the computational complexities of the FFTbased and time-domain methods with respect to the length of ultrasound signal segments. The simulation results using numerical phantoms show that, with the optimized autocorrelation weighting function, we only need approximately 3% of the full set of data points. In addition to that, because the proposed optimization technique requires a fixed number of data points to calculate the spectral centroid, the execution time is constant as the length of the data segment increases, whereas the execution time of the conventional FFT-based method is increased. Analysis of the computational complexities between the proposed method and the conventional FFT-based method presents O(N) and O(Nlog2N), respectively.
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17
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Hosokawa A. Numerical investigation of ultrasound reflection and backscatter measurements in cancellous bone on various receiving areas. ULTRASONICS 2014; 54:1237-1244. [PMID: 24128942 DOI: 10.1016/j.ultras.2013.09.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 09/02/2013] [Accepted: 09/04/2013] [Indexed: 06/02/2023]
Abstract
In this study, new ultrasound reflection and backscatter measurements in cancellous bone using a membrane-type hydrophone are proposed. A membrane hydrophone made of a piezoelectric polymer film mounted on an annular frame allows an incident ultrasound wave to pass through its aperture because it has no backing material. Therefore, in measurements using the membrane hydrophone, the receiving area could be located independently from the transmitting area. In addition, the size and shape of the receiving area, which corresponded to those of the electrode deposited on the piezoelectric film, could be arranged in various ways. To investigate the validity of the proposed measurements, before bench-top experiments, the reflected and backscattered waves from cancellous bone were numerically simulated using a finite-difference time-domain method. The reflection and backscatter parameters were measured on various receiving areas, and their correlation coefficients with the structural parameters in the cancellous bone were derived. The simulated results suggested that appropriate receiving areas for the reflection and backscatter measurements could exist and that the proposed measurements could be more effective for evaluating bone properties than conventional measurements.
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Affiliation(s)
- Atsushi Hosokawa
- Department of Electrical and Computer Engineering, Akashi National College of Technology, 679-3 Nishioka, Uozumi, Akashi 674-8501, Japan.
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18
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Rubert N, Varghese T. Scatterer number density considerations in reference phantom-based attenuation estimation. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:1680-96. [PMID: 24726800 PMCID: PMC4178544 DOI: 10.1016/j.ultrasmedbio.2014.01.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 01/20/2014] [Accepted: 01/27/2014] [Indexed: 05/05/2023]
Abstract
Attenuation estimation and imaging have the potential to be a valuable tool for tissue characterization, particularly for indicating the extent of thermal ablation therapy in the liver. Often the performance of attenuation estimation algorithms is characterized with numerical simulations or tissue-mimicking phantoms containing a high scatterer number density (SND). This ensures an ultrasound signal with a Rayleigh distributed envelope and a signal-to-noise ratio (SNR) approaching 1.91. However, biological tissue often fails to exhibit Rayleigh scattering statistics. For example, across 1647 regions of interest in five ex vivo bovine livers, we obtained an envelope SNR of 1.10 ± 0.12 when the tissue was imaged with the VFX 9L4 linear array transducer at a center frequency of 6.0 MHz on a Siemens S2000 scanner. In this article, we examine attenuation estimation in numerical phantoms, tissue-mimicking phantoms with variable SNDs and ex vivo bovine liver before and after thermal coagulation. We find that reference phantom-based attenuation estimation is robust to small deviations from Rayleigh statistics. However, in tissue with low SNDs, large deviations in envelope SNR from 1.91 lead to subsequently large increases in attenuation estimation variance. At the same time, low SND is not found to be a significant source of bias in the attenuation estimate. For example, we find that the standard deviation of attenuation slope estimates increases from 0.07 to 0.25 dB/cm-MHz as the envelope SNR decreases from 1.78 to 1.01 when estimating attenuation slope in tissue-mimicking phantoms with a large estimation kernel size (16 mm axially × 15 mm laterally). Meanwhile, the bias in the attenuation slope estimates is found to be negligible (<0.01 dB/cm-MHz). We also compare results obtained with reference phantom-based attenuation estimates in ex vivo bovine liver and thermally coagulated bovine liver.
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Affiliation(s)
- Nicholas Rubert
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
| | - Tomy Varghese
- Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
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19
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Jiang YQ, Liu CC, Li RY, Wang WP, Ding H, Qi Q, Ta D, Dong J, Wang WQ. Analysis of apparent integrated backscatter coefficient and backscattered spectral centroid shift in Calcaneus in vivo for the ultrasonic evaluation of osteoporosis. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:1307-17. [PMID: 24642217 DOI: 10.1016/j.ultrasmedbio.2013.12.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 12/16/2013] [Accepted: 12/17/2013] [Indexed: 05/10/2023]
Abstract
The purposes of our study were to evaluate the correlation among apparent integrated backscatter coefficient (AIB), spectral centroid shift (SCS) of ultrasonic backscatter signals and bone mineral density (BMD) and to examine the effectiveness of ultrasound variables as predictors of osteoporosis. A total of 1011 persons aged 21-80 y old were included. All study participants underwent BMD measurements of the lumbar spine (LSBMD) and the femoral neck (FNBMD). The participants also underwent calcaneal measurements to determine AIB and SCS with central frequencies of 3.5 (one transducer) and 5.0 MHz (the other transducer). AIB decreased with age and was positively correlated with BMD, while SCS increased with age and was negatively correlated with BMD. The correlation coefficient of SCS with LSBMD and FNBMD at 3.5 MHz was -0.72 and -0.70, respectively. The correlation coefficient at 5.0 MHz was -0.75 and -0.74, respectively. The correlation coefficient of AIB with LSBMD and FNBMD at 3.5 MHz was 0.65 and 0.63. The correlation coefficient at 5.0 MHz was 0.59 and 0.55, respectively. The correlation between SCS and BMD was significantly better than the correlation between AIB and BMD. Using receiver operating characteristic analysis, a significant difference was found between the areas under the curve for SCS and AIB at 3.5 MHz (0.781 vs. 0.715, respectively, p < 0.05), as well as at 5.0 MHz (0.782 vs. 0.709, respectively, p < 0.05). The optimum T-score threshold for SCS was -1.3 for both transducers. The sensitivity and specificity of SCS at 3.5 MHz and 5.0 MHz for the optimum threshold were 64%, 85%, 63% and 86%, respectively. In conclusion, the correlations among the ultrasound parameters and BMDs are strong. SCS performs better than AIB in differentiating patients with osteoporosis. Ultrasound variables may be taken into consideration as predictors of osteoporosis in the future considering its portability.
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Affiliation(s)
- Yun-qi Jiang
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, PR China
| | - Cheng-cheng Liu
- Electronic Engineering Department of Fudan University, Shanghai, PR China
| | - Ruo-yu Li
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, PR China
| | - Wen-ping Wang
- Department of Ultrasonography, Zhongshan Hospital, Fudan University, Shanghai, PR China
| | - Hong Ding
- Department of Ultrasonography, Zhongshan Hospital, Fudan University, Shanghai, PR China
| | - Qing Qi
- Department of Ultrasonography, Zhongshan Hospital, Fudan University, Shanghai, PR China.
| | - Dean Ta
- Electronic Engineering Department of Fudan University, Shanghai, PR China.
| | - Jian Dong
- Department of Orthopaedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, PR China.
| | - Wei-qi Wang
- Electronic Engineering Department of Fudan University, Shanghai, PR China
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20
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Nam K, Zagzebski JA, Hall TJ. Quantitative assessment of in vivo breast masses using ultrasound attenuation and backscatter. ULTRASONIC IMAGING 2013; 35:146-61. [PMID: 23493613 PMCID: PMC3676873 DOI: 10.1177/0161734613480281] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Clinical analysis of breast ultrasound imaging is done qualitatively, facilitated with the ultrasound breast imaging-reporting and data system (US BI-RADS) lexicon, which helps to standardize imaging assessments. Two descriptors in that lexicon, "posterior acoustic features" and the "echo pattern" within a mass, are directly related to quantitative ultrasound (QUS) parameters, namely, ultrasound attenuation and the average backscatter coefficient (BSC). The purpose of this study was to quantify ultrasound attenuation and backscatter in breast masses and to investigate these QUS properties as potential differential diagnostic markers. Radio frequency (RF) echo signals were from patients with breast masses during a special ultrasound imaging session prior to core biopsy. Data were also obtained from a well characterized phantom using identical system settings. Masses include 14 fibroadenomas and 10 carcinomas. Attenuation for the acoustic path lying proximal to the tumor was estimated offline using a least squares method with constraints. BSCs were estimated using a reference phantom method (RPM). The attenuation coefficient within each mass was assessed using both the RPM and a hybrid method, and effective scatterer diameters (ESDs) were estimated using a Gaussian form factor model. Attenuation estimates obtained with the RPM were consistent with estimates done using the hybrid method in all cases except for two masses. The mean slope of the attenuation coefficient versus frequency for carcinomas was 20% greater than the mean slope value for the fibroadenomas. The product of the attenuation coefficient and anteroposterior dimension of the mass was computed to estimate the total attenuation for each mass. That value correlated well with the BI-RADS assessment of "posterior acoustic features" judged qualitatively from gray scale images. Nearly all masses were described as "hypoechoic," so no strong statements could be made about the correlation of echo pattern findings in BI-RADS with the averaged BSC values. However, most carcinomas exhibited lower values for the frequency-average BSC than fibroadenomas. The mean ESD alone did not differentiate the mass type, but fibroadenomas had greater variability in ESDs within the ROI than that found for invasive ductal carcinomas. This study demonstrates the potential to use attenuation and QUS parameters associated with the BSC as quantitative descriptors.
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Affiliation(s)
- Kibo Nam
- Department of Medical Physics, University of Wisconsin-Madison, WI 53705, USA
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21
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Ghorayeb SR, Rooney DM. Ultrasonic evaluation of bone quality in cadaver ilia. Ann Biomed Eng 2013; 41:939-51. [PMID: 23299828 DOI: 10.1007/s10439-012-0737-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 12/26/2012] [Indexed: 10/27/2022]
Abstract
Several imaging modalities have traditionally been utilized to assess bone health. However, none of these standards is capable of providing a clear rendition or display of the damaged bone layers caused, for instance, by osteoporosis. This study examines the use of ultrasound for non-invasive monitoring of bone quality in bone samples with various degrees of porosity. A user-defined region of interest (ROI) in the iliac portion of extracted human cadaver coxal bones is monitored and quantified. Raster C-scan images of the ROI were acquired and compared to basic physical measurements, and to bone scans using dual energy X-ray absorptiometry (DXA). A quantitative measure of the superficial sub-surface composite matrix (ScM) content was analyzed using linear regression with all physical and DXA measures. The trend in the degree of percent bone loss (PBL) measured by ultrasound (US) was found to be closely paralleled with that measured by DXA (R(2) = 0.82, p < .0005). Also, the trend in which PBL (US) correlated with bone mineral density (BMD) (R(2) = 0.62, p < .01) was found to exhibit a similar behavior when the latter was compared to dry mass density (DmD) of the bone samples (R(2) = 0.63, p < .01). However, when PBL (DXA) was compared to DmD, it did reveal a better linearity (R(2) = 0.69, p < .005) than the one obtained when PBL (US) was compared with the same DmD (R(2) = 0.45, p < .05). A similar outcome was observed when PBL (US) was compared with percent porosity (R(2) = 0.51, p < .05), as opposed to the better linearity exhibited between PBL (DXA) and porosity (R(2) = 0.86, p < .0005). Despite these slight variations, further analyses on the statistical significance between these correlations suggest that ultrasound can be an effective imaging technique in assessing the degree of bone damage, and can be used to assess the structural integrity of bones.
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Affiliation(s)
- Sleiman R Ghorayeb
- School of Engineering and Applied Sciences, Ultrasound Research Laboratory, Hofstra University, Hempstead, NY 11549, USA.
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22
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Nam K, Rosado-Mendez IM, Wirtzfeld LA, Ghoshal G, Pawlicki AD, Madsen EL, Lavarello RJ, Oelze ML, Zagzebski JA, O’Brien WD, Hall TJ. Comparison of ultrasound attenuation and backscatter estimates in layered tissue-mimicking phantoms among three clinical scanners. ULTRASONIC IMAGING 2012; 34:209-21. [PMID: 23160474 PMCID: PMC3667595 DOI: 10.1177/0161734612464451] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Backscatter and attenuation coefficient estimates are needed in many quantitative ultrasound strategies. In clinical applications, these parameters may not be easily obtained because of variations in scattering by tissues overlying a region of interest (ROI). The goal of this study is to assess the accuracy of backscatter and attenuation estimates for regions distal to nonuniform layers of tissue-mimicking materials. In addition, this work compares results of these estimates for "layered" phantoms scanned using different clinical ultrasound machines. Two tissue-mimicking phantoms were constructed, each exhibiting depth-dependent variations in attenuation or backscatter. The phantoms were scanned with three ultrasound imaging systems, acquiring radio frequency echo data for offline analysis. The attenuation coefficient and the backscatter coefficient (BSC) for sections of the phantoms were estimated using the reference phantom method. Properties of each layer were also measured with laboratory techniques on test samples manufactured during the construction of the phantom. Estimates of the attenuation coefficient versus frequency slope, α(0), using backscatter data from the different systems agreed to within 0.24 dB/cm-MHz. Bias in the α(0) estimates varied with the location of the ROI. BSC estimates for phantom sections whose locations ranged from 0 to 7 cm from the transducer agreed among the different systems and with theoretical predictions, with a mean bias error of 1.01 dB over the used bandwidths. This study demonstrates that attenuation and BSCs can be accurately estimated in layered inhomogeneous media using pulse-echo data from clinical imaging systems.
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Affiliation(s)
- Kibo Nam
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | | | - Lauren A. Wirtzfeld
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, IL, USA
| | - Goutam Ghoshal
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, IL, USA
| | - Alexander D. Pawlicki
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, IL, USA
| | - Ernest L. Madsen
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | - Roberto J. Lavarello
- Sección Electricidad y Electrónica, Pontificia Universidad Católica del Perú, Lima, Perú
| | - Michael L. Oelze
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, IL, USA
| | - James A. Zagzebski
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
| | - William D. O’Brien
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, IL, USA
| | - Timothy J. Hall
- Department of Medical Physics, University of Wisconsin, Madison, WI, USA
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23
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Kim H, Heo SW. Time-domain calculation of spectral centroid from backscattered ultrasound signals. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2012; 59:1193-1200. [PMID: 22711414 DOI: 10.1109/tuffc.2012.2309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Spectral centroid estimation from backscattered ultrasound RF signals is the preliminary step for quantitative ultrasound analysis in many medical applications. The traditional approach of estimating the spectral centroid in the frequency domain takes a long time because discrete Fourier transform (DFT) processing for each RF segment is required. To avoid this, we propose time-domain methods to estimate the spectral centroid in this paper. First, we derive the continuous-time-domain equations for the spectral centroid estimation using Parseval's theorem and Hilbert transform theory. Then, we extend the method to the discrete-time domain to ease the implementation while maintaining the same accuracy as the calculation in the frequency domain. From the result, we observe that it is not practical to apply the discrete-time equations directly, because a high sampling rate is needed to approximate the time derivative in the discrete-time domain. Therefore, we also derive the feasible version of the discrete-time equations using a circular autocorrelation function, which has no constraints on the sampling rate for real RF signals acquired from pulse-echo ultrasound systems. Simulation results using numerical phantoms show that the time-domain calculation is approximately 4.4 times faster on average than the frequency-domain method when the software's built-in functions were used. The average estimation error compared with that of the frequency-domain method using DFT is less than 0.2% for the entire propagation depths. The proposed time-domain approach to estimate the spectral centroid can be easily implemented in real-time ultrasound systems.
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Affiliation(s)
- Hyungsuk Kim
- Department of Electrical Engineering, Kwangwoon University, Seoul, Korea
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24
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Nam K, Zagzebski JA, Hall TJ. Simultaneous backscatter and attenuation estimation using a least squares method with constraints. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:2096-104. [PMID: 21963038 PMCID: PMC3223333 DOI: 10.1016/j.ultrasmedbio.2011.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 07/29/2011] [Accepted: 08/10/2011] [Indexed: 05/04/2023]
Abstract
Backscatter and attenuation variations are essential contrast mechanisms in ultrasound B-mode imaging. Emerging quantitative ultrasound methods extract and display absolute values of these tissue properties. However, in clinical applications, backscatter and attenuation parameters sometimes are not easily measured because of tissues inhomogeneities above the region-of-interest (ROI). We describe a least squares method (LSM) that fits the echo signal power spectra from a ROI to a three-parameter tissue model that simultaneously yields estimates of attenuation losses and backscatter coefficients. To test the method, tissue-mimicking phantoms with backscatter and attenuation contrast as well as uniform phantoms were scanned with linear array transducers on a Siemens S2000. Attenuation and backscatter coefficients estimated by the LSM were compared with those derived using a reference phantom method (Yao et al. 1990). Results show that the LSM yields effective attenuation coefficients for uniform phantoms comparable to values derived using the reference phantom method. For layered phantoms exhibiting nonuniform backscatter, the LSM resulted in smaller attenuation estimation errors than the reference phantom method. Backscatter coefficients derived using the LSM were in excellent agreement with values obtained from laboratory measurements on test samples and with theory. The LSM is more immune to depth-dependent backscatter changes than commonly used reference phantom methods.
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Affiliation(s)
- Kibo Nam
- Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, WI, USA.
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25
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Nam K, Rosado-Mendez IM, Rubert NC, Madsen EL, Zagzebski JA, Hall TJ. Ultrasound attenuation measurements using a reference phantom with sound speed mismatch. ULTRASONIC IMAGING 2011; 33:251-63. [PMID: 22518955 PMCID: PMC3384730 DOI: 10.1177/016173461103300404] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Ultrasonic attenuation may be measured accurately with clinical systems and array transducers by using reference phantom methods (RPM) to account for diffraction and other system dependencies on echo signals. Assumptions with the RPM are that the speeds of sound in the sample (c(sam)) and in the reference medium (c(ref)) are the same and that they match the speed assumed in the system beamformer (c(bf)). This work assesses the accuracy of attenuation measurements by the RPM when these assumptions are not met. Attenuation was measured for two homogeneous phantoms, one with a speed of sound of 1500 m/s and the other with a sound speed of 1580 m/s. Both have an attenuation coefficient approximately equal to that of the reference, in which the speed of sound is 1540 m/s. Echo signals from the samples and the reference were acquired from a Siemens S2000 scanner with a 9L4 linear array transducer. Separate acquisitions were obtained with c(bf) at its default value of 1540 m/s and when it was set at values matching the speeds of sound of the phantoms. Simulations were also performed using conditions matching those of the experiment. RPM-measured attenuation coefficients exhibited spatially-dependent biases when c(sam) differed from c(df) and c(ref). Mean errors of 19% were seen for simulated data, with the maximum errors in attenuation measurements occurring for regions of interest near the transmit focus. Biases were minimized (mean error with simulated data was 5.6%) using c(bf) that matched c(sam) and assuring that power spectra used for attenuation computations in the sample are from precisely the same depth as those from the reference. Setting the transmit focus well beyond the depth range used to compute attenuation values minimized the bias.
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Affiliation(s)
- Kibo Nam
- Department of Medical Physics, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
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26
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Heo SW, Kim H. A novel power spectrum calculation method using phase-compensation and weighted averaging for the estimation of ultrasound attenuation. ULTRASONICS 2010; 50:592-599. [PMID: 20083291 DOI: 10.1016/j.ultras.2009.12.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 12/15/2009] [Accepted: 12/16/2009] [Indexed: 05/28/2023]
Abstract
An estimation of ultrasound attenuation in soft tissues is critical in the quantitative ultrasound analysis since it is not only related to the estimations of other ultrasound parameters, such as speed of sound, integrated scatterers, or scatterer size, but also provides pathological information of the scanned tissue. However, estimation performances of ultrasound attenuation are intimately tied to the accurate extraction of spectral information from the backscattered radiofrequency (RF) signals. In this paper, we propose two novel techniques for calculating a block power spectrum from the backscattered ultrasound signals. These are based on the phase-compensation of each RF segment using the normalized cross-correlation to minimize estimation errors due to phase variations, and the weighted averaging technique to maximize the signal-to-noise ratio (SNR). The simulation results with uniform numerical phantoms demonstrate that the proposed method estimates local attenuation coefficients within 1.57% of the actual values while the conventional methods estimate those within 2.96%. The proposed method is especially effective when we deal with the signal reflected from the deeper depth where the SNR level is lower or when the gated window contains a small number of signal samples. Experimental results, performed at 5MHz, were obtained with a one-dimensional 128 elements array, using the tissue-mimicking phantoms also show that the proposed method provides better estimation results (within 3.04% of the actual value) with smaller estimation variances compared to the conventional methods (within 5.93%) for all cases considered.
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Affiliation(s)
- Seo Weon Heo
- School of Electronic and Electrical Engineering, Hongik University, Seoul 121-791, Republic of Korea
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27
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Karjalainen JP, Töyräs J, Riekkinen O, Hakulinen M, Jurvelin JS. Ultrasound backscatter imaging provides frequency-dependent information on structure, composition and mechanical properties of human trabecular bone. ULTRASOUND IN MEDICINE & BIOLOGY 2009; 35:1376-84. [PMID: 19525060 DOI: 10.1016/j.ultrasmedbio.2009.03.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2009] [Revised: 02/26/2009] [Accepted: 03/08/2009] [Indexed: 05/10/2023]
Abstract
The strength as well as the acoustic properties of trabecular bone are determined by its structure and composition. Consequently, tissue structure and compositional properties also affect the ultrasound propagation in bone. The diagnostic potential of ultrasound has not been fully exploited in clinical quantitative ultrasound devices. The aim of this study was to investigate the ability of quantitative ultrasound pulse-echo imaging, conducted over a broad range of frequencies (1 to 5 MHz), to predict the mechanics, composition and microstructure of trabecular bone. Ultrasound reflection and backscatter parameters correlated significantly with the ultimate strength of the trabecular bone and the bone volume fraction (r=0.76-0.90, n=20, p<0.01). Ultrasound backscatter associated significantly (independently of bone structure or mineral content) with the collagen content of the bone matrix (r=0.75, r(adjusted)=0.66, p<0.01). Interestingly, the applied ultrasound frequency seemed to relate the sensitivity of ultrasound backscatter to different properties of trabecular bone. At frequencies ranging from 1 to 3.5 MHz, the ultrasound backscatter associated significantly with the tissue mechanical and structural parameters. At 5MHz, the composition of the bone matrix was a more significant determinant of the measured backscatter. This study provides useful information for optimizing the use of pulse-echo measurements, and thereby further emphasizes the diagnostic potential of the ultrasound backscatter measurements of trabecular bone.
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28
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Hasegawa H, Matsuura M, Sato H, Yamamoto T, Kanai H. Imaging of gaps in digital joints by measurement of ultrasound transmission using a linear array. ULTRASOUND IN MEDICINE & BIOLOGY 2009; 35:382-394. [PMID: 19111971 DOI: 10.1016/j.ultrasmedbio.2008.09.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 08/18/2008] [Accepted: 09/15/2008] [Indexed: 05/27/2023]
Abstract
In orthodontic dentistry for young subjects, it is important to assess the degree of growth of the jaw bones to determine the optimum time for treatment. The structure of the digital joint changes with age, with such changes correlating to the degree of bone growth (including jaw bones). There are two gaps in the digital joint of a young subject, one of which disappears with aging. In the present study, a method for noninvasive assessment of such change in the structure of a digital joint was examined, in which continuous-wave ultrasound is radiated to a digital joint by a single-element ultrasonic transducer. This continuous ultrasound, which passes through the digital joint, is received by a linear array ultrasonic probe situated opposite the transducer. The probe simultaneously realizes pulse-echo imaging and imaging of transmission ultrasound, which passes through the joint. Using this experimental apparatus, the existence and position of a gap can be detected clearly by imaging the transmission ultrasound on a pulse-echo image. In basic experiments, continuous-wave ultrasound generated by a planar or focused transducer was radiated to a gap between two acrylic bars, which simulated that in a digital joint; transmission ultrasound, which passed through the gap, was measured with a linear array probe. The basic experimental results showed that a gap with a width >0.4 mm is detectable and that the width at half maximum of the amplitude profile of the received transmission ultrasound that passed through the gap correlated with the width of the gap. Furthermore, in the preliminary in vivo experiments, transmission ultrasound that passed through two gaps in the case of a child was clearly imaged by the proposed method, and that which passed through only one gap in the case of an adult was also imaged. These results show the possibility for the use of the proposed method to noninvasively assess the change in the structure of a joint as a result of aging.
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Affiliation(s)
- Hideyuki Hasegawa
- Graduate School of Biomedical Engineering, Tohoku University, Sendai, Japan.
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Zheng R, Le LH, Sacchi MD, Lou E. Broadband ultrasound attenuation measurement of long bone using peak frequency of the echoes. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2009; 56:396-399. [PMID: 19251527 DOI: 10.1109/tuffc.2009.1049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The traditional peak frequency formulation requires the knowledge of the signal wavelet. We improved and applied the method to estimate attenuation for homogeneous silicon rubber and bovine cortical bone without recourse to the wavelet assumption. The estimated values for rubber and bone samples are 6.59 +/- 0.28 dB/MHz/cm and 4.59 +/- 1.09 dB/MHz/cm, respectively, as compared with 6.33 +/- 0.19 dB/ MHz/cm and 5.00 +/- 1.10 dB/MHz/cm, respectively, by the spectral ratio method.
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Garra BS, Locher M, Felker S, Wear KA. Measurements of ultrasonic backscattered spectral centroid shift from spine in vivo: methodology and preliminary results. ULTRASOUND IN MEDICINE & BIOLOGY 2009; 35:165-8. [PMID: 18723270 PMCID: PMC8243223 DOI: 10.1016/j.ultrasmedbio.2008.06.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 04/25/2008] [Accepted: 06/13/2008] [Indexed: 05/25/2023]
Abstract
Ultrasonic backscatter measurements from vertebral bodies (L3 and L4) in nine women were performed using a clinical ultrasonic imaging system. Measurements were made through the abdomen. The location of a vertebra was identified from the bright specular reflection from the vertebral anterior surface. Backscattered signals were gated to isolate signal emanating from the cancellous interiors of vertebrae. The spectral centroid shift of the backscattered signal, which has previously been shown to correlate highly with bone mineral density (BMD) in human calcaneus in vitro, was measured. BMD was also measured in the nine subjects' vertebrae using a clinical bone densitometer. The correlation coefficient between centroid shift and BMD was r = -0.61. The slope of the linear fit was -160 kHz / (g/cm(2)). The negative slope was expected because the attenuation coefficient (and therefore magnitude of the centroid downshift) is known from previous studies to increase with BMD. The centroid shift may be a useful parameter for characterizing bone in vivo.
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Affiliation(s)
| | | | | | - Keith A. Wear
- US Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, MD, USA
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Wear KA. Mechanisms for attenuation in cancellous-bone-mimicking phantoms. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2008; 55:2418-25. [PMID: 19049921 PMCID: PMC6935503 DOI: 10.1109/tuffc.949] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Broadband ultrasound attenuation (BUA) in cancellous bone is useful for prediction of osteoporotic fracture risk, but its causes are not well understood. To investigate attenuation mechanisms, 9 cancellous-bone-mimicking phantoms containing nylon filaments (simulating bone trabeculae) embedded within soft-tissue-mimicking fluid (simulating marrow) were interrogated. The measurements of frequency-dependent attenuation coefficient had 3 separable components: 1) a linear (with frequency) component attributable to absorption in the soft-tissue-mimicking fluid, 2) a quasilinear (with frequency) component, which may include absorption in and longitudinal-shear mode conversion by the nylon filaments, and 3) a nonlinear (with frequency) component, which may be attributable to longitudinal-longitudinal scattering by the nylon filaments. The slope of total linear (with frequency) attenuation coefficient (sum of components #1 and #2) versus frequency was found to increase linearly with volume fraction, consistent with reported measurements on cancellous bone. Backscatter coefficient measurements in the 9 phantoms supported the claim that the nonlinear (with frequency) component of attenuation coefficient (component #3) was closely associated with longitudinal-longitudinal scattering. This work represents the first experimental separation of these 3 components of attenuation in cancellous bone-mimicking phantoms.
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Affiliation(s)
- Keith A Wear
- U.S. Food and Drug Administration, Center for Devices and Radiological Health, Silver Spring, MD, USA.
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Kim H, Varghese T. Hybrid spectral domain method for attenuation slope estimation. ULTRASOUND IN MEDICINE & BIOLOGY 2008; 34:1808-19. [PMID: 18621468 DOI: 10.1016/j.ultrasmedbio.2008.04.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Revised: 03/27/2008] [Accepted: 04/18/2008] [Indexed: 05/05/2023]
Abstract
Attenuation estimation methods for medical ultrasound are important because attenuation properties of soft tissue can be used to distinguish between benign and malignant tumors and to detect diffuse disease. The classical spectral shift method and the spectral difference method are the most commonly used methods for the estimation of the attenuation; however, they both have specific limitations. Classical spectral shift approaches for estimating ultrasonic attenuation are more sensitive to local spectral noise artifacts and have difficulty in compensating for diffraction effects because of beam focusing. Spectral difference approaches, on the other hand, fail to accurately estimate attenuation coefficient values at tissue boundaries that also possess variations in the backscatter. In this paper, we propose a hybrid attenuation estimation method that combines the advantages of the spectral difference and spectral shift methods to overcome their specific limitations. The proposed hybrid method initially uses the spectral difference approach to reduce the impact of system-dependent parameters including diffraction effects. The normalized power spectrum that includes variations because of backscatter changes is then filtered using a Gaussian filter centered at the transmit center frequency of the system. A spectral shift method, namely the spectral cross-correlation algorithm is then used to compute spectral shifts from these filtered power spectra to estimate the attenuation coefficient. Ultrasound simulation results demonstrate that the estimation accuracy of the hybrid method is better than the centroid downshift method (spectral shift method), in uniformly attenuating regions. In addition, this method is also stable at boundaries with variations in the backscatter when compared with the reference phantom method (spectral difference method). Experimental results using tissue-mimicking phantom also illustrate that the hybrid method is more robust and provides accurate attenuation estimates in both uniformly attenuating regions and across boundaries with backscatter variations. The proposed hybrid method preserves the advantages of both the spectral shift and spectral difference approaches while eliminating the disadvantages associated with each of these methods, thereby improving the accuracy and robustness of the attenuation estimation.
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Affiliation(s)
- Hyungsuk Kim
- Department of Medical Physics, The University of Wisconsin-Madison, Madison, WI 53706, USA.
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Wear KA. Ultrasonic scattering from cancellous bone: a review. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2008; 55:1432-41. [PMID: 18986932 PMCID: PMC6935504 DOI: 10.1109/tuffc.2008.818] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This paper reviews theory, measurements, and computer simulations of scattering from cancellous bone reported by many laboratories. Three theoretical models (binary mixture, Faran cylinder, and weak scattering) for scattering from cancellous bone have demonstrated some consistency with measurements of backscatter. Backscatter is moderately correlated with bone mineral density in human calcaneus in vitro (r(2) = 0.66 - 0.68). Backscatter varies approximately as frequency cubed and trabecular thickness cubed in human calcaneus and femur in vitro. Backscatter from human calcaneus and bovine tibia exhibits substantial anisotropy. So far, backscatter has demonstrated only modest clinical utility. Computer simulation models have helped to elucidate mechanisms underlying scattering from cancellous bones.
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Affiliation(s)
- K A Wear
- Center for Devices & Radiol. Health, U.S. Food & Drug Adm., Silver Spring, MD, USA.
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Hoffmeister BK, Johnson DP, Janeski JA, Keedy DA, Steinert BW, Viano AM, Kaste SC. Ultrasonic characterization of human cancellous bone in vitro using three different apparent backscatter parameters in the frequency range 0.6-15.0 mhz. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2008; 55:1442-52. [PMID: 18986933 DOI: 10.1109/tuffc.2008.819] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Ultrasonic techniques based on measurements of apparent backscatter may provide a useful means for diagnosing bone diseases such as osteoporosis. The term "apparent" means that the backscattered signals are not compensated for the frequency-dependent effects of attenuation and diffraction. We performed in vitro apparent backscatter measurements on 23 specimens of human cancellous bone prepared from the left and right femoral heads of seven donors. A mechanical scanning system was used to obtain backscattered signals from each specimen at several sites. Scans were performed using five different ultrasonic transducers with center frequencies of 1, 2.25, 5, 7.5, and 10 MHz. The -6 dB bandwidths of these transducers covered a frequency range of 0.6-15.0 MHz. The backscattered signals were analyzed to determine three ultrasonic parameters: apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), and time slope of apparent backscatter (TSAB). Linear regression analysis was used to examine the correlation of these ultrasonic parameters with five measured physical characteristics of the specimens: mass density, X-ray bone mineral density, Young's modulus, yield strength, and ultimate strength. A total of 75 such correlations were examined (3 ultrasonic parameters x 5 specimen characteristics x 5 transducers). Good correlations were observed for AIB using the 5 MHz (r = 0.70 - 0.89) and 7.5 MHz (r = 0.75-0.93) transducers; for FSAB using the 2.25 MHz (r = 0.70 - 0.88), 5 MHz (r = 0.79 - 0.94), and 7.5 MHz (r = 0.80 - 0.92) transducers; and for TSAB using the 5 MHz (r = 0.68 - 0.89), 7.5 MHz (r = 0.75 - 0.89), and 10 MHz (r = 0.75 - 0.92) transducers.
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Ta DA, Zhou GH, Wang WQ, Yu JG. Measurement of spectral maximum shift of ultrasonic backscatter signals in cancellous bone. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2005:2703-6. [PMID: 17282797 DOI: 10.1109/iembs.2005.1617028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The feasibility of assessing cancellous bone from the Spectral Maximum Shift (SMS) of the backscattered ultrasonic signal is investigated. And the SMS of backscatter signals from bovine tibiae cancellous bone in vitro were measured and discussed. The spectral maximum of the backscattered signal downshift with increases of the apparent density of cancellous bone. When the bone suffered from osteoporosis, the density will reduce. Therefore, compared with the backscattered signal spectrum in the normal cancellous bone, the osteoporotic cancellous bones have small SMS of backscattered signal. According to the size of SMS, the status of cancellous bone and the degree of osteoporotic fracture risk may be assessed. On the other hand, techniques based on ultrasonic backscatter offer the advantage that only one ultrasonic transducer rather than two transducers is required to perform measurements. The operation of measurement is convenient and simple in assessment of cancellous bone status and diagnosis of osteoporosis.
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Affiliation(s)
- De-An Ta
- Department of Electronic Engineering, Fudan University, Shanghai 200433, China. e-mail:
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Abstract
As was true 10 years ago, tremendous interest surrounds the concept of "bone quality," as shown by the intense and growing research activity in the field. The urgency to advance knowledge in this area is motivated by the need to understand not only the causes of increased skeletal fragility with aging and disease, but also the mechanisms by which drugs reduce fracture risk. As reflected in the preceding articles, in the past decade collaborations between biologists, physicists, engineers and clinicians have led to new insights regarding the biological, material and structural features that contribute to skeletal fragility. Despite these new insights, important issues remain unresolved. Our challenges lie in identifying, describing and understanding the totality of features and characteristics that determine a bone's ability to resist fracture, and using this information to identify new therapeutic targets and develop better biomarkers and noninvasive imaging modalities. This summary is intended to integrate reports in the literature with presentations and discussions that occurred during the meeting, to highlight areas of consensus and those of continued controversy, and thus to identify critical areas for future research.
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